An example of a prior gun-shaped game controller is disclosed in U.S. Pat. No. 6,672,962. The controller is thus formed to include a barrel, a trigger unit, and a grip unit. Installed on the tip of the barrel is an artificial retina unit which takes in game images from a monitor screen. Attached to the trigger unit is a trigger lever that can be operated with a player's finger. A start switch, a cross-direction key, and a reload switch are installed in a position on the top of the grip unit of the controller main body, and corresponds to the hammer section of an actual gun. In the operation of a shooting game, and when the trigger lever is pulled, the screen of a monitor is brightened for a moment. The light is detected with a light detection means in the gun-type controller, and the point of impact is determined based on the light detection signal.
In the gun-type controller as described in the '962 patent, the trigger unit is located below the barrel. However, if the trigger level is operated with an index finger, and the cross-direction key operated with a thumb, the controller is difficult to operate while maintaining a stable holding state because the controller itself needs to be supported by holding the grip unit with only the remaining three fingers.
Furthermore, in the gun-type controller according to the '962 patent, because the cross-direction key is installed in a position corresponding to the hammer section, there is a distance between the section operated with the index finger and the section operated with the thumb, requiring extension of the fingers for holding it, which in turn limits the movable range of the fingers, making it difficult to move them simultaneously.